Automatic sprinkler or fire extinguisher and other fire device



April 25, 1933. s BARCLAY 1,905,676

ER OR FIRE EXTINGUISHER AND OTHER FIRE DEVICE AUTOMATIC SPRINKL Filed March 30, 1931 Patented Apr. 25, 1933 SIDNEY FRASER BARCLAY, OF MAITGHESTER, ENGLAND, ASSIGNOR T0 GENERAL FIRE EXTINGUISHER COMPANY, OF PROVIDENCE, RHODE ISLAND, A CORPORATION. OF

DELAWARE AUTOMATIC SPRINKLER OR FIRE EXTINGUISHER AND OTHER FIRE DEVICE Application filed March 30, 1931, Serial No. 526,509, and in Great Britain April 15, 1930.

This invention relates to automatic sprinklers, fire extinguishers and other fire control devices of the type utilizing a fused quartz, glass or like bulb (containing a liquid and a small bubble) as the element to be destroyed when a predetermined temperature is reached so as to release the sprinkler valve, a fire door or the like or to open windows or other parts such as are usually controlled by thermally responsive links or struts.

In practice the liquid (e. g. acetone) employed within the bulb is chosen so as in conjunction with the degree to which the bulb is filled to ensure that the bulb is shattered only when a predetermined temperature is reached. 1 have found, however, that when bulbs are placed in situations where they are subjected to changes of temperature which as a maximum do not reach the shattering temperature but approach the same, there is a liability of the bulb cracking and releasing its contents without becoming shattered. Thus the bulb is rendered inoperative but the part controlled by the bulb is not released.

By research I have found that the heating of the bulb to a relatively high temperature, which is, however, lower than the shattering temperature, and its subsequent cooling are accompanied by certain changes in the physical state of the contents of the bulb. Thus at a certain relatively high temperature the bubble which has become smaller with the temperature increase, disappears, but on cooling the bulb, the bubble does not reappear at the temperature at which it disappeared, but at a lower temperature and its reappearance is accompanied by a sound like a click. My investigations have led me to the conclusion that during the cooling period and before the bubble reappears, a tension within the liquid is induced and causes the walls of the bulb to tend to collapse inwards until a point is reached at which rupture between the liquid and the bulb surface, or within the liquid, takes place accompanied by the sudden release of the compressive stress on the material of the bulb by hydraulic shock and by the reappearance of the bubble. In other words, the bulb under the conditions stated is submitted to reversed stresses and impact stresses of appreciable magnitude in comparison with the ultimate strength of the material of the bulb, which can result in fatigue of the material of the bulb with consequent failure of the latter in service.

Theobject of my present invention is to provide simple and effective means for over- 7 coming the aforesaid defect of the bulb type thermally responsive elements under the indicated conditions as to temperature variations to which they may besubjected.

My invention comprises the addition to the thermally expansive liquid by which the bulb isshattered at a predetermined temperature of a material or materials which destroy or reduce to a low value the tensile stress induced in such liquid prior to the reappearance of the bubble as before described.

In the accompanying drawing Figure 1 is a medial section of a sprinkler employing a bulbvcharged in accordance with the pres ent invention; and r V Figure 2 is an elevation of the bulb alone.

Referring more particularly to the drawing the sprinkler comprises a valve or carried by a cap I) which is engaged by a bulb 0 supported by the hollow cone (Z. The latter engages the yoke e of the sprinkler frame. The bulb cmay be made of quartz, glass or the like frangible material and is charged with a liquid adapted upon being heated to a predetermined degree to completely shatter the bulb. When charging the bulb with this liquid, all the space of the bulb is filled except a small portion which is herein referred to as the bubble f. The liquid placed in the bulb has, in accordance with this invention, i

added material or materials which affect the tensile strength of the liquid under certain conditions which occur in the bulb.

The added material may consist of a colloidal matter and may, for example, be such the temperature at which the bulb is intended to operate, about 1% of the volume in the bulb is undissolved dyestuff. Suitable dyestufis are red Celatine and methyl violet.

5 Other dyestuffs may, however, be employed.

It may also consist of porous substances such as graphite or meerschaum, materials presenting a large specific area, and consequently carrying appreciable quantities of ad sorbed gases, such as nitro-cellulose, and insoluble non-porous hard materials in a finely ground state, such as powdered glass, or finely ground crystalline substances such as carborundum. If finely powdered graphite which has been prepared in an electric furnace be the material which is to be added to the liquid in the bulb, the extent of such addition may be from 0.5 to 1% of the weight of the liquid. If amorphous sulphur be em- ,ployed in place of graphite, about 1% of J such sulphur may be added to the liquid. Or about 1 0 of finely powdered vulcanite may be added to the liquid for filling the bulb.

By the addition of a material which de- 0 7,5,stroys or reduces to a low value the tenslle stress in the thermally expansive liquld durfailure of the walls of the bulb.

ing the cooling of the liquid from a high temperature to one at which the bubble reappears, I prevent fatigue and premature l/Vhat I claim is V 1. In bulbs containing a liquid and a bubble for use in automatic sprinklers, fire extinguishers and other fire control devices, the

" addition to the thermally expansive liquid by which the bulb is shattered at a predetermined temperature of a material or materials which destroy or reduce to a low value the tensile stress induced in such liquid prior to the reappearance on. cooling of the bubble after its disappearance upon heating of the bulb to a temperature lower than the shattering temperature.

2. Bulbs for use in fire control devices containing a thermally expansive liquid and a bubble with an added material for destroying or reducing to a low value the tensile stress induced in such liquid prior to the reappearance on cooling of the bubble after its disappearance upon heating of the bulb to a temperature lower than the shattering temperature, as set forth.

3.. A frangible bulb containing a bubble and a thermally expansive liquid by which the bulb is shattered at a predetermined temperature and a porous substance of large specific area and capable of reducing the ten sile stress induced in the liquid prior to the reappearance of the bubble on cooling after its disappearance upon heating the bulb to a temperature lower than the shattering temperature.

4. A frangible bulb containing a bubble and a thermally expansive liquid by which the bulb is shatteredat a predetermined temand a thermally expansive liquid by which the bulb is shattered at a predetermined temperature and a colloidal substance in afinely comminuted state and capable of reducing the tensile stress induced in the liquid prior to the reappearance of the bubble on cooling after its disappearance upon heating the bulb to a temperature lower. than temperature.

In testimony whereof I have signed my name to this saecification.

SIDNE FRASER BARCLAY.

the shattering 

